Hi guys, we have a 2011 F750 with a ISB 6.7 cummins. the issue we are have is as follows. Customer complained of a turbo surging and loss of power condition. this truck has no fault codes. at any given time while under a load, more so at lower RPM heavy load conditions, the turbo will start to surge and a loss of power is the result. now when this happens the EGR valve is being commanded to open by the ECM so we are loosing all drive pressure. at idle no load the ECM will also command the EGR valve to open and close at any given time anywhere from 0 to 100% sporadically. this also happens under a load. we have had ECM tested by Cummins, as well as updated to the latest calibration. We have another truck with the same engine here and we have swapped all of the following sensors in hopes of stumbling across something. .EGR valve .EGR differential pressure sensor .EGR temp sensor .MAF sensor .MAP sensor . Turbo .VGT actuator .EBP sensor EBP sensor tube

This truck also has a new complete Aftertreatment system due to a cracked DPF. All fuel parameters are normal. we have tested wiring to just about everything. the only thing that we have not changed is the aftertreatment intake NOX sensor.

Has anyone on here ever experienced a similar situation with a medium duty? we are open to any suggestions. thanks.

Rex Varilek
Owner/Technician
Precision Diesel
Red Oak, Iowa, USA